Touch screen controller using differential signal processing

Abstract

A touch screen controller using differential signal processing includes a charge amplifier, a first variable gain amplifier, one or more second variable gain amplifiers, a channel integrator, and a linearizer. The charge amplifier converts a charge output from a touch panel into a voltage and output a single-ended signal. The first variable gain amplifier removes an offset except touch information existing on a path sensing signal. The one or more second variable gain amplifiers removes an offset between channels while referring to a line signal input to the first variable gain amplifier. The channel integrator performs integration on the signal output from the first and the second variable gain amplifier and return a common reference to a pixel result, and the linearizer performs linearization by detecting a linearization factor and a phase error of the output signal of the channel integrator.

1 . A touch screen controller using differential signal processing, the touch screen controller comprising:
 a charge amplifier configured to convert a charge output from a touch panel into a voltage and output a single-ended signal;   a first variable gain amplifier configured to remove an offset except for touch information existing on a path sensing signal preset for differential processing of the single-ended signal output from the charge amplifier;   at least one second variable gain amplifier configured to remove an offset between channels while referring to a line signal input to the first variable gain amplifier;   a channel integrator configured to perform an integration on the signal output from the first and the at least one second variable gain amplifiers from a first channel and returning a common reference to a pixel result; and   a linearizer configured to perform a linearization by detecting a linearization factor and a phase error of an output signal of the channel integrator.   
     
     
         2 . The touch screen controller of  claim 1 , wherein the touch panel comprises at least one path in which driving is performed on an X coordinate and sensing is performed on a Y coordinate. 
     
     
         3 . The touch screen controller of  claim 1 , wherein the first and the at least one second variable gain amplifiers receive a reference signal and records the received reference signal in a first sensing channel as a common reference between lines. 
     
     
         4 . The touch screen controller of  claim 3 , wherein the reference signal is one of a sine waveform, a pulse waveform, and a triangular waveform. 
     
     
         5 . The touch screen controller of  claim 1 , further comprising:
 an anti-alias filter configured to perform anti-alias filtering on the single-ended signal output from the charge amplifier and transmit an anti-alias filtered signal to the first and the at least one second variable gain amplifiers.   
     
     
         6 . The touch screen controller of  claim 1 , further comprising:
 a demodulator configured to demodulate an anti-alias filtered signal and transmit the demodulated anti-alias filtered signal to the first and the at least one second variable gain amplifiers.   
     
     
         7 . The touch screen controller of  claim 6 , further comprising:
 an anti-alias filter configured to perform anti-alias filtering on the single-ended signal output from the charge amplifier and transmit the anti-alias filtered signal to the demodulator.   
     
     
         8 . The touch screen controller of  claim 1 , further comprising:
 an anti-alias filter configured to perform anti-alias filtering on the signal output from the first and the at least one second variable gain amplifiers and transmit an anti-alias filtered signal to the channel integrator.   
     
     
         9 . The touch screen controller of  claim 1 , further comprising:
 an analog-digital converter configured to convert an analog signal output from the first and the at least one second variable gain amplifiers to a digital signal and transmit the digital signal to the channel integrator.   
     
     
         10 . The touch screen controller of  claim 1 , further comprising:
 a demodulator configured to detect a phase of the output signal from the channel integrator, scramble a random noise by applying an absolute function to the output signal, and transmit a scrambled signal to the linearizer.   
     
     
         11 . The touch screen controller of  claim 1 , wherein the first variable gain amplifier removes all offsets except for the touch information existing on the path sensing signal by obtaining a difference between continuous paths adjacent to each other. 
     
     
         12 . A touch screen controller using differential signal processing, the touch screen controller comprising:
 a charge amplifier configured to convert a charge output from a touch panel into a voltage and output a single-ended signal;   a demodulator configured to convert a phase of a demodulated waveform to a phase of each path sensing signal included, in the output single-ended signal;   a first variable gain amplifier configured to remove an offset except for touch information existing on a path sensing signal preset for differential processing of a signal output from the demodulator;   at least one second variable gain amplifier configured to remove an offset between channels while referring to a line signal input to the first variable gain amplifier;   a channel integrator configured to perform an integration on a signal output from the first and the at least one second variable gain amplifiers from a first channel and returning a common reference to a pixel result; and   a linearizer configured to perform a linearization by detecting a linearization factor and a phase error of an output signal of the channel integrator.   
     
     
         13 . The touch screen controller of  claim 12 , further comprising:
 an anti-alias filter configured to perform anti-alias filtering on a signal output from the demodulator and transmit the anti-alias filtered signal to the first and the at least one second variable gain amplifier.   
     
     
         14 . The touch screen controller of  claim 12 , further comprising:
 an anti-alias filter configured to perform anti-alias filtering on the single-ended signal output from the charge amplifier and transmit the anti-alias filtered signal to the demodulator.   
     
     
         15 . The touch screen controller of  claim 12 , further comprising:
 a sample and hold circuit configured to sample a signal output from the first and the at least one second variable gain amplifier within a preset period of time; and   a multiplexer configured to convert the sampled signal into a single-ended signal and transmit the single-ended signal to the channel integrator.   
     
     
         16 . The touch screen controller of  claim 15 , further comprising:
 an analog digital converter configured to convert an analog signal output from the multiplexer into a digital signal and transmit the digital signal to the channel integrator.   
     
     
         17 . The touch screen controller of  claim 15 , wherein the channel integrator is configured to detect phase information based on the signal output from the first and the at least one second variable gain amplifier in order to minimize a phase error. 
     
     
         18 . The touch screen controller of  claim 12 , wherein the linearizer comprises:
 a first linearizer configured to reduce a differential phase error based on the signal output from the first and the at least one second variable gain amplifier; and   a second linearizer configured to detect touch position information of the touch panel by a linearization factor.   
     
     
         19 . The touch screen controller of  claim 12 , wherein the first variable gain amplifier removes all offsets except for the touch information existing on the path sensing signal by obtaining a difference between continuous paths adjacent to each other. 
     
     
         20 . The touch screen controller of  claim 19 , wherein an input phase difference of the first and the at least one second variable gain amplifiers is reduced based on the obtained difference between continuous paths adjacent to each other.